The park has grown gradually to its present size. In 1907 the area between the Kuiseb and Swakop rivers was proclaimed as 'Game Reserve No 3'. Later it was augmented by the addition of Sandwich Harbour in 1941.

In 1956 the Kuiseb Canyon and Swakop River Valley were added, along with the Welwitschia Plains, and in 1968 the park was renamed The Namib Desert Park. In 1979 a large area of what was the protected 'Diamond Area No 2' was added, including Sesriem and Sossusvlei, and the park was officially joined to the Naukluft Park, creating the Namib-Naukluft National Park.

Most recently, in 1986, the rest of 'Diamond Area No 2' was added, taking the park's southern boundary as far south as the main road to Lüderitz, and increasing its area to its present size of 49,768km2 – larger than Switzerland, or about the same as Maryland and New Jersey combined.